CN105730673B

CN105730673B - Landing gear bay roof of improved design

Info

Publication number: CN105730673B
Application number: CN201511005885.5A
Authority: CN
Inventors: D·贝莱; G·加朗; F·卢瓦永; A·勒加尔代; S·普
Original assignee: Airbus Operations SAS
Current assignee: Airbus Operations SAS
Priority date: 2014-12-30
Filing date: 2015-12-29
Publication date: 2019-12-13
Anticipated expiration: 2035-12-29
Also published as: ES2586396R1; ES2586396A2; FR3031080A1; US20160185451A1; FR3031080B1; ES2586396B2; US10343768B2; CN105730673A

Abstract

The invention relates to an improvement in the design of the nose (20) of a landing gear bay (12) of an aircraft, said landing gear nose comprising: a first main stiffening structure (44a) and a second main stiffening structure (44b) spaced apart from each other in a transverse direction (Y) of the top and provided respectively with mounting means allowing the articulation of the structural element (60a) of the first landing gear (42a) and with mounting means allowing the articulation of the structural element (60b) of the second landing gear (42 b); and-a membrane (46) connecting the first reinforcement main structure (44a) and the second reinforcement main structure (44b) while being interposed between them along the transversal direction (Y).

Description

Landing gear bay roof of improved design

Technical Field

the present invention relates to an aircraft, in particular an aircraft with a main landing gear bay. More specifically, the invention relates to the roof of the landing gear bay and the environmental facilities of the roof.

The invention is suitable for all types of aircraft, in particular commercial aircraft.

background

On existing aircraft, the top of the main landing gear bay is typically used to isolate a pressurized upper bay, typically the cabin of the aircraft, from a lower bay forming the landing gear bay for receiving two main landing gears laterally spaced from each other.

The unpressurized landing gear bay is delimited at the front by a wing box integrated in the fuselage, which is intended to connect the two wings of the aircraft in the transverse direction on respective sides of the wing box. Furthermore, the landing gear bay roof is typically fixedly mounted on the upper skin of the wing box. Thus, in the case of a vertical manoeuvre of the aircraft at the utmost, the deformation in the transverse direction allowed by the centre wing box can produce a forced parasitic deformation of the landing gear bay roof in that same direction. To limit the negative effects of these parasitic deformations, a more flexible top can be designed. However, this solution may not be suitable when the top must absorb mechanical forces directly from structural elements of the landing gear, such as the struts.

Therefore, an optimal design of the environmental facilities at the top of the main landing gear bay is required, in particular with the aim of solving this problem of deformation coordination between the top of the landing gear bay and the wing box of the central wing.

object of the Invention

To this end, the invention consists firstly in a landing gear bay top for an aircraft for forming a pressurized obstacle (barriere de pressure) between a pressurized upper bay and a landing gear bay for receiving a first main landing gear and a second main landing gear, said landing gear bay top comprising:

-a first and a second main stiffening structure, spaced apart from each other in a transverse direction of the landing gear bay top and provided respectively with mounting means allowing articulation of the structural elements of the first main landing gear and with mounting means allowing articulation of the structural elements of the second landing gear; and

-a membrane connecting a first reinforcement main structure and a second reinforcement main structure while being interposed between the first reinforcement main structure and the second reinforcement main structure in the transverse direction.

It is worth noting that the present invention is a break from the prior art solutions in which the design of the landing gear bay roof is relatively uniform in its lateral direction. In fact, the invention skillfully divides the roof into three distinct parts, namely two stiffening main structures, which are intended to form the rigid part of the roof, and an intermediate diaphragm, which is inherently more flexible, with a function similar to that of a mechanical trip between the two main structures. In this configuration, the inherent rigidity of the main structure makes it possible to satisfactorily absorb the mechanical forces transmitted directly into these structures by the main landing gear. Furthermore, because of the tripping in the transverse direction between the two main structures, each structure is loaded only by a transverse narrowing of the wing box of the central wing (solliciter). This considerably reduces the occurrence of parasitic deformations on the stiffening primary structure, in particular in the case of extremely vertical manoeuvres of the aircraft.

in other words, the design of the landing gear bay roof according to the invention allows to satisfactorily solve the problem of the coordination of deformations between the landing gear bay roof and the wing box of the central wing, while being able to suitably absorb mechanical forces directly coming from the main landing gear.

The present invention has at least one of the following optional technical features, alone or in combination.

The membrane has a circular shape so as to define a recess in the upper surface of the landing gear bay roof. Preferably, it may have a U-shaped cross section, perfectly optimally absorbing the pressurization forces, while guaranteeing mechanical tripping in the transverse direction between the two reinforcement main structures.

The membrane sheet has a radius of curvature in the range of 400 to 500 mm.

the diaphragm plate has a first end portion and a second end portion, the first end portion and the second end portion are fixed to the first reinforcing main structure and the second reinforcing main structure, respectively, and a main portion of the diaphragm plate is disposed between the first end portion and the second end portion. Preferably, these three elements are made in one piece.

The first end and the second end each have a substantially perpendicular tangent. However, these tangents may be at an angle to the vertical, such as a maximum acute angle of 20 °.

The main portion of the membrane sheet has a substantially constant thickness, preferably about 0.7 to 1.5 mm.

The main part of the membrane sheet is free of transverse stiffeners. Conversely, the longitudinal stiffeners may be attached to the membrane sheet, or made in one piece with the membrane sheet.

the ratio between the width in the transverse direction and the height in the vertical direction of the main part of the membrane sheet is between 0.7 and 1.3.

The diaphragm is made of a metallic or elastomer-based material.

The mounting means allowing the articulation of the structural elements of the first main landing gear are arranged substantially centrally on the first main reinforcing structure; furthermore, the mounting means allowing the structural element of the second main landing gear to be articulated are arranged substantially centrally on the second main reinforcing structure.

The ratio between the transverse extent of the membrane sheet and the transverse extent of the first and second stiffening main structures is between 0.1 and 0.2.

The first main reinforcement structure and the second main reinforcement structure each have a plate or a group of reinforcement plates and at least one longitudinal beam and at least one transverse beam.

The invention also consists in an assembly for an aircraft comprising:

A centre-wing box for connecting two wings in a transverse direction on respective sides of the centre-wing box,

A landing gear bay top as described above, arranged behind a centre wing box, on which the first and second main stiffening structures of the landing gear bay top are each fixedly mounted,

-a first and a second main landing gear, the structural elements of which are mounted in an articulated manner on mounting means of a first and a second main stiffening structure equipping the landing gear well roof, and

preferably, the system, for example a pipe, runs longitudinally in a concave portion defined by a membrane on top of the landing gear bay.

Preferably, the first and second main landing gears each have a leg hinged about a hinge axis inclined to the transverse direction and inclined to the longitudinal direction.

Finally, the invention consists in an aircraft having such a landing gear bay top or such an assembly.

Other advantages and features of the present invention will appear in the non-limiting detailed description which follows.

Drawings

The description will proceed with reference to the accompanying drawings, in which:

FIG. 1 is an exploded perspective view of the aircraft of the present invention;

FIG. 2 is an enlarged perspective view of a fuselage section incorporating the present invention;

FIG. 3 is a side view of a portion of an assembly according to a preferred embodiment of the present invention;

FIGS. 4 and 5 are perspective views of the assembly shown from different angles;

FIG. 6 is an exploded perspective view of the assembly shown in FIGS. 4 and 5;

FIG. 7 is an enlarged perspective detail view of the landing gear bay top equipped with the assembly shown in FIGS. 4 to 6;

FIG. 7a is a bottom perspective view of the landing gear bay top shown in FIG. 7;

FIG. 8 is a cross-sectional partial view of the landing gear bay top taken along section line VIII-VIII of FIG. 7;

FIG. 9 shows the landing gear bay top in plan view with a chart schematically illustrating the degree of deformation in the lateral direction in the case of a strong vertical manoeuvre of the aircraft; and

Figure 10 schematically shows the deformation of the landing gear bay roof during dynamic landing.

Detailed Description

fig. 1 shows an aircraft 100 of the commercial aircraft type of the present invention. Throughout the following description, generally, X corresponds to the longitudinal direction of the aircraft, Y corresponds to a direction oriented transversely with respect to the longitudinal direction, and Z corresponds to the vertical or altitude direction, these three directions X, Y and Z being mutually orthogonal.

On the other hand, the terms "forward" and "aft" are considered with respect to the direction of forward movement of the aircraft caused by the thrust exerted by the turbojet engine, this direction being schematically illustrated by the arrow 3.

The aircraft 100 includes a fuselage 102 with two wings 104 secured to the fuselage 102 at a fuselage section 102a of the present invention.

The body portion 102a is shown in more detail in fig. 2. It comprises a fuselage outer skin 106 supported by a substantially circular or oval fuselage frame 108. A floor 110 is provided in the fuselage section 102a, above which an upper pressurized cabin, i.e. a passenger cabin 112 of the aircraft, is provided. Below the floor 110, in front of the fuselage section 102a, a first under-floor plenum 116a is provided, which is typically used for storing aircraft-specific technical equipment and/or cargo. The under-floor plenum 116a is bounded at the rear by a central wing box 2, which is also disposed below the floor 100. The centre wing box 2 extends laterally across the entire width of the fuselage section 102 a. The centre wing box typically has an upper skin 4, a lower skin 6, a front skin 10, a rear skin 8, and side closure panels and internal stiffeners. The centre-wing box serves to connect the two wings 104 in the direction Y on the respective sides of the centre-wing box.

At the rear, the fuselage portion 102a has a landing gear bay 12 for receiving two main landing gears (not shown in fig. 2) spaced from each other along the direction Y. A landing gear bay 12, generally parallelepiped-shaped, is delimited at the front by the rear skin 8 of the central wing box 2, which is integrated into the fuselage portion 102 a. The fuselage is open at the bottom so that the landing gear can be stowed and lowered, the opening being closed by a flap which reconfigures the fuselage in the stowed position of the landing gear.

At the rear, the landing gear bay 12 is delimited by an airtight bottom 16 which separates it from a second underfloor pressurized cabin 116b, which is also used for storing technical equipment and/or goods.

At the top end, the gear well 12 is delimited by a gear well roof 20 which extends over the entire transverse width of the fuselage section 102a on which it is integrally mounted. The roof 20 of the present invention is located below the floor 110. Furthermore, it should be noted that above the roof forming the pressure obstacle, an intermediate pressure chamber is provided, which is defined between the floor 110 and the roof 20. For simplicity of the drawing, the passenger cabin and the intermediate pressurized cabin are indicated with the same reference numeral 112.

The landing gear bay top therefore constitutes a pressurisation barrier between the pressurised passenger cabin 112 above the top and the non-pressurised landing gear bay 12 which receives the main landing gear. In this respect, the arrows on fig. 3 show the supercharging region of the aircraft, which is formed by the following elements from the front to the rear: the rear skin 10 of the centre wing box 2, the upper skin 4 of the centre wing box, the landing gear bay roof 20, and the airtight bottom 16 of the landing gear bay 12.

The assembly 40 of the present invention will now be described with reference to figures 4 to 6. The assembly 40 for packaging into the fuselage portion 102a generally comprises a central wing box 2, a landing gear bay 12, in particular delimited by a top 20 and an airtight bottom 16, and two main landing gears 42a, 42 b.

One of the features of the present invention is the design of the top 20, which breaks the prior art solution. In fact, the top is divided in the direction Y into three distinct portions contiguous to each other, so as to act as a supercharging obstacle over the entire width of the fuselage. More precisely, there is a first main stiffening structure 44a and a second main stiffening structure 44b, which are arranged symmetrically with respect to the median plane XZ of the aircraft. The outer longitudinal edges of the first structure 44a are intended to be fixed directly to the fuselage, to the outer skin and/or to the frame of the fuselage. Likewise, the outer longitudinal edge of the second structure 44b is secured to the fuselage on the opposite side. The inner longitudinal edges of the two structures 44a, 44b are connected by a membrane 46 which ensures a mechanical tripping action between the two structures in the direction Y.

In other words, the landing-gear bay top 20 can be considered as an assembly (ensemble) made up of three parts, described in detail below, respectively a flexible central part 46 and two more rigid outer parts 44a, 44b, the central part connecting the two more rigid outer parts, the central part having a lower resistance to telescoping, in particular in the direction Y, than the two outer parts. Preferably, the ratio between the two anti-telescoping capabilities is about 1/1000.

The assembly 40 also includes a landing gear support structure. Similarly, a first support structure 48a is provided at the rear of the landing gear bay 12, secured to the roof portion 20 and offset laterally outwardly relative thereto. Furthermore, the first support structure is fixed to a fuselage frame 50 located behind the airtight bottom 16, the lower end of the frame 50 itself being fixed to a fuselage section 52 extending over the entire length of the fuselage section. As can be seen more clearly in figure 6, the part 52 reconfigures the bottom of the fuselage beneath the centre wing box 2 and then extends rearwards by a narrowed width portion 54 which runs longitudinally through the opening of the landing gear bay 12. The beam-shaped portion 54 divides the opening into two half-openings, each for the passage of one landing gear 42a, 42 b. The beam-shaped portion is also capable of receiving a landing gear door.

The first support structure 48a supports the first landing gear 42 a. It has a standard design with one leg 56a supporting the landing gear wheel at one of its ends and hinged to the first structure 48a at its opposite end. The hinge axis 58a of the leg 56a is preferably inclined in three directions X, Y and Z so that the leg can be inclined in directions X and Y when the landing gear is in its stowed position. In this regard, it should be noted that fig. 5 shows the landing gear in two positions, namely a lowered position and a stowed position. In the stowed position, the landing gear is disposed in a plane XY with its legs inclined in a rearwardly opening V-shape (only one of the two stowed landing gears is visible in figure 5).

In addition to the landing gear leg 56a, the landing gear 42a includes other structural elements, such as one or more lowering actuators and a sprag (brace) 60a, typically made up of segments hinged to one another, the lower end of which is hingedly mounted on the leg 56 a. The opposite ends of the diagonal brace 60a are hingedly mounted to the lower end surface of the first reinforcing structure 44a of the roof 20 as will be described later.

furthermore, it should be noted that the symmetrical arrangement is used for mounting a second main landing gear 42b associated with a second reinforcing structure 44b of the crown 20 (associator). In the drawings, elements of this configuration bear the same reference numerals as those just described for the configuration associated with the first drop frame 42a, except that the suffix a is replaced with a suffix b after each reference numeral.

Referring now to fig. 7, 7a and 8, the landing gear bay top 20 is illustrated in more detail. The first and second stiffening main structures 44a, 44b are symmetrical with respect to a mid-plane XZ. Also, only the first structure 44a will be described later.

the first and second stiffening main structures comprise a set of stiffening webs 60 arranged substantially in the same plane XY. These plates are reinforced by means of longitudinal stiffeners 62, for example made in one piece with the plates, or attached to the plates.

The structure 44a further comprises two longitudinal beams 64, a first longitudinal beam extending along the outer edge of the set of plates and a second longitudinal beam extending along the inner edge of the set of plates.

The length of the outer longitudinal beam 64 is substantially equal to the total length of the roof 20 in the direction X. Which is intended to be attached to the fuselage longitudinally, at the front, and is followed by a box-shaped main corner piece (coin demalle)66 that can be fixed to the rear skin of the centre wing box 2. The inner stringers 64 have a considerable length, with a front portion projecting relative to the plate 60 in order to be fixed to the upper skin 4 of the centre wing box.

A plurality of cross members 68 connect the two longitudinal beams 64. For example, there are three beams 68, and thus each beam 68 extends across the entire width of the main structure 44 a. Intermediate beams 70 interconnect the cross beams 68. There are two intermediate beams 70 that are connected to the central beam 68 at the same point 72 in the direction X, for example, on respective sides of both sides of the central beam 68.

Beam 70 and beams 64, 68 are fixedly mounted on the upper surface of plate 62 in a plane XY. The beams may be tilted in each direction X and Y.

On the lower surface of the plate 62, in a perpendicular projection to the point 72 or in the vicinity thereof, there is provided a mounting member 74 enabling the articulation of the end of the sprag 60a, as can be seen in figure 7 a. In addition, the mounting members 74 are substantially centered on the main structure 44 a. The mounting means are for example in the form of a joint provided with holes for passing the hinge pins of the sprags 60 a.

Thus, the forces transmitted by the struts 60a on dynamic landing are transmitted at the centre point 72 and can then be distributed within the reinforcing structure 44a via the spars 70, the spars 64, 68 and the reinforcing plates 60 and transmitted into the centre wing box 2.

The constituent elements of each primary structure 44a, 44b may be made of metallic or composite materials.

The two stiffening main structures 44a, 44b are over most of the width of the roof 20. More precisely, their respective transversal amplitudes (retende), indicated in fig. 7 by E1a and E1b, are much greater than the transversal amplitude E2 of the membrane 46 in the direction Y. In this regard, the ratio between the total amplitude of the structures 44a, 44b and the amplitude of the diaphragm 46 is preferably between 0.1 and 0.2.

The first function of the diaphragm 46 is to ensure continuity of the pressurization barrier between the two main structures 44a, 44b just described. The diaphragm may be metallic, but is preferably made of an elastomer-based material.

As can be seen well in fig. 8, the membrane plate has a circular shape, preferably with a U-shaped cross-section, with a radius of curvature (raw de court) R between 400 and 500 mm. The diaphragm 46 also has a vertical mid-plane XZ as its plane of symmetry, with the arms of the U being disposed on either side of this plane.

the interior of the U-shape defines a recessed portion 76 which is open at the top end, in which a system 78, preferably a duct for conditioned air, travels (cheminer). Thus, the space defined by recessed portion 76 is utilized to advantage to enable system 78 to pass longitudinally along top portion 20. The U-shape generally projects downwardly into the landing gear bay 12, i.e. is recessed downwardly relative to the reinforcement plate 60. This retraction does not interfere with the wheels of the stowed landing gear, which is shown partially in figure 8 as a profile 80.

the diaphragm 46 has a first end 82a and a second end 82b which are fixed to the main structures 44a, 44b, respectively, more precisely to the inner longitudinal beams 64 of these structures. The fastening takes place by means of rivets, bolts or similar fastening elements. Due to the U-shape, each end 82a, 82b has a substantially vertical tangent, so that, advantageously, the vertical air pressure generated at said each end is zero.

A main portion 84 of the diaphragm 46 is disposed between the two ends 82a, 82b, forming a U-shaped circular portion. Preferably, these portions 82a, 82b, 84 are made in one piece, having substantially the same thickness, which is about 0.7 to 1.5 mm.

In order to guarantee a good mechanical tripping between the two main structures 44a, 44b in the direction Y, the diaphragm 46 is preferably free of transverse stiffeners and, as mentioned above, has a substantially constant thickness. Advantageously, such mechanical tripping is easily implemented due to the U-shape of the diaphragm 46, the ratio between the width "l" of the main portion 84 of the diaphragm in the direction Y and the height "H" in the direction Z being between 0.7 and 1.3.

Because of this mechanical tripping in the direction Y between the two main structures 44a, 44b, each structure is loaded only by a lateral constriction of the centre wing box 2. Furthermore, in the case of a strong vertical manoeuvre of the aircraft causing a large deformation of the centre wing box 2 in the direction Y, the occurrence of parasitic deformations of the primary structures 44a, 44b is limited. The expansion and contraction observed in the direction Y with this loading situation is shown on the graph of fig. 9. The diagram shows that the large deflections observed on the upper skin of the centre wing box 2 produce only parasitic small deflections on each of the two main structures 44a, 44 b.

furthermore, fig. 10 shows a small deformation of the two main structures 44a, 44b in case of dynamic landing, in fact the intrinsic rigidity of these structures makes it possible to suitably absorb mechanical forces directly coming from the main landing gear. These forces are then transmitted to the centre wing box 2 where they tend to be attracted and disappear.

It is obvious that various changes may be made by those skilled in the art to which the invention pertains, and that the invention is given by way of non-limiting example only.

Claims

1. An aircraft landing gear bay (12) roof (20) for forming a pressurized barrier between a pressurized upper bay (112) and a landing gear bay (12) for receiving first (42a) and second (42b) main landing gears, the landing gear bay roof comprising:

-a first main stiffening structure (44a) and a second main stiffening structure (44b) spaced apart from each other along a transverse direction (Y) of the landing gear bay top and provided respectively with a mounting (74) allowing articulation of a structural element (60a) of the first main landing gear (42a) and with a mounting (74) allowing articulation of a structural element (60b) of the second main landing gear (42 b); and

-a membrane (46) connecting said first (44a) and second (44b) stiffening main structures, interposed between them along the transversal direction (Y).

2. The landing gear bay roof according to claim 1, wherein the membrane (46) has a circular shape so as to define a recess (76) in an upper surface of the landing gear bay roof.

3. Landing gear bay roof according to claim 1 or 2, wherein the membrane (46) has a radius of curvature (R) between 400 and 500 mm.

4. the landing gear bay roof according to claim 1 or 2, wherein the membrane (46) has a first end (82a) and a second end (82b) fixed to the first and second main stiffening structures (44a, 44b), respectively, a main portion (84) of the membrane being disposed between the first and second ends.

5. the landing gear bay roof according to claim 4, wherein the first end (82a) and the second end (82b) each have a substantially vertical tangent.

6. The landing gear bay roof according to claim 4, wherein the main portion (84) of the membrane plate (46) has a substantially constant thickness.

7. landing gear bay roof according to claim 4, characterized in that the main portion (84) of the membrane (46) is free of transverse stiffeners.

8. Landing gear bay roof according to claim 4, wherein the ratio between the width (I) in the transverse direction (Y) and the height (H) in the vertical direction (Z) of the main portion (84) of the membrane plate (46) is between 0.7 and 1.3.

9. Landing gear bay roof according to claim 1 or 2, wherein the membrane plate (46) is made of a metallic or elastomer-based material.

10. The landing gear bay roof according to claim 1 or 2, characterised in that the mounting means (74) allowing articulation of the structural element (60a) of the first main landing gear (42a) are arranged substantially centred on the first stiffening main structure (44 a); and in that the mounting means (74) allowing articulation of the structural element (60b) of the second main landing gear (42b) are arranged substantially centred on the second reinforcing main structure (44 b).

11. Landing gear bay roof according to claim 1 or 2, wherein the ratio between the transverse amplitude (E2) of the membrane (46) and the transverse amplitudes (E1a, E1b) of the first and second stiffening main structures (44a, 44b) is between 0.1 and 0.2.

12. Landing gear bay roof according to claim 1 or 2, characterised in that the first and second main stiffening structures (44a, 44b) each have a plate or a set of stiffening plates (60) and at least one longitudinal beam (64) and at least one transverse beam (68).

13. The landing gear bay roof of claim 6, wherein the thickness is approximately 0.7 to 1.5 millimeters.

14. An assembly (40) for an aircraft, characterized in that it comprises:

A centre-wing box (2) for connecting the two wings (104 ) in a transverse direction (Y) on respective sides of the centre-wing box,

-the landing gear bay top (20) according to any one of the preceding claims, being arranged behind a centre wing box (2), the first and second main stiffening structures (44a, 44b) of the landing gear bay top each being fixedly mounted on the centre wing box (2),

-first and second main landing gears (42a, 42b) whose structural elements (60a, 60b) are hingedly mounted on mounting means (74, 74) of first and second main stiffening structures (44a, 44b) equipping the landing gear bay roof.

15. Assembly according to claim 14, characterized in that the first and second main landing gears (42a, 42b) each have one leg (56a, 56b) articulated about an articulation axis (58a, 58b) inclined with respect to the transverse direction (Y) and inclined with respect to the longitudinal direction (X).

16. the assembly of claim 14, further comprising a system (78) running longitudinally in a recess (76) defined by a membrane (46) of the landing gear bay roof (20).

17. An assembly according to claim 14, characterized in that the system (78) is a pipe.

18. an aircraft (100) characterized in that it comprises a landing gear bay top (20) according to any one of claims 1 to 13 or an assembly (40) according to any one of claims 14 to 17.